The present invention relates to a pyrotechnic valve making it possible either to open an initially closed pipe, or to close an initially open pipe.
At present, pyrotechnic valves are widely used for opening a pipe through which passes a fluid, particularly on aircraft or spacecraft. The operating principle consists of using gases under a high pressure produced by a pyrotechnic device, in order to displace a rigid member. The latter can be a sliding valve core having one or more proturberances, in order that its displacement has the effect of raising a valve, so that the passage of the fluid is possible. In other types of valve, the mobile rigid member perforates a pipe or cuts off a precut end fitting. This second type of valve is used more particularly in spacecraft, e.g. for the thrust of a propulsive fluid mass, a gas being stored under high pressure (a few hundred bars), the opening of the valve enabling it to expand and enter the pressurized liquid tank which is at about 10 bars, whic is sufficient to force the liquid into the circuit of the power plant. Another spatial application is the analysis of the atmosphere surrounding a planet. The measuring chamber, which is linked with the downstream part of the valve, is placed under a vacuum prior to launch. The upstream part fills with gas, when the craft arrives in the atmosphere to be studied and the opening of the valve brings about the filling of the measuring chamber by suction.
It is clear that the valve must have a perfect tightness, particularly in the second case, in order not to falsify the measurements, or when the fluid circulating in the valve represents a danger to the environment. However, most of the existing systems suffer from the disadvantage of not having an adequate seal or tightness between the zone in which are located the gases produced by the pyrotechnic devices and the fluid passage zone. As a result, such valves do not comply with certain severe requirements, and cannot be used in pneumatic systems carried by spacecraft, where it is required that the environment is not polluted by their operation.